Micropumps are used for various technical fields, particularly in the medical field, in order to convey small quantities of fluids in a precise manner. Micromechanical manufacturing methods are used for producing micropumps, silicon being used, for example, which may be simply and precisely patterned using appropriate depositing and etching methods.
This type of micropump is described in U.S. Pat. No. 6,390,791, which is produced on an SOI wafer. This micropump is made up of a triple stack having two glass wafers and an SOI wafer located in between. In order to produce a pump diaphragm, a monocrystalline silicon layer of the SOI wafer is used, for the production, for example, a dry etching method (DRIE) being used for patterning the silicon layer, and a sacrificial oxide etching method being used for exposing the patterns. The disadvantages of this method include that, in the high-rate etching method, the etching depth is established by the etching time, and is therefore not precisely controllable. If one does not keep precisely to the etching time, the result is a thickness variation of the functional layer of which the pump diaphragm is formed. This leads to different pump characteristics of the micropump. In addition, in the conventional method, it is disadvantageous that sacrificial oxide etching steps are required which have the effect of a nonreproducible undercut etching depth, since there is no lateral etch stop.